[Elecraft] Balun BL2

[Vic Rosenthal 4X6GP/K2VCO]

How hot it gets is determined by 1) the SWR and 2) the configuration of 
the antenna/feedline -- how much common mode power it has to dissipate.

I have a DX Engineering balun rated 5 kW continuous and 10 kW 
intermittent which /overheated/ on some bands when running 1 kW -- until 
I added capacitance or inductance on the antenna side of the balun to 
cancel out the reactance and at the same time detune the feedline for 
common mode current. Now it stays cold.

73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/

On 27 May 2016 04:04, jsodus at comcast.net wrote:
> Hello,
> I'm contemplating buying the BL2 balun.
> It would be connected to 450-ohm transmission-line, which would go to a version of W1AB's "killer-antenna", sized for 20m on a 31' jackite-pole.
>
> A reviewer of the BL2, on eham five years ago, commented about heat and signal-loss.
> The heat and signal-loss concern me, not at the QRP-level but higher wattage.
> I realize it is spec'd at 250 W but how hot does it get?
>
> I've looked for data about insertion-loss for the BL2 and came up short there.
> Hopefully someone has measured the insertion-loss and could share that data.
>
> The "elecraft BL2 assembly and operating manual" has the cores as ferrite material.
> But ferrites exhibit non-linear properties, so the loss may be a function, not only of frequency, but also drive-level.
> Insertion-loss shows up as heat and that heat affects the properties of the ferrite.
>
> As I wrote above, I'm not concerned about QRP operation.
> If I put it into operation on FD and but take my KX3 home for the day, what happens if a club-member connects his 100+ W rig to the antenna-system to operate thru the night?
> TIA for any reply.
>
> 73 Jerry KM3K
> KX3 #6088